With recent advances in material science, and the consumer driven desire for larger and more powerful engines, recreational fishing vessels presently have more available power output than at anytime in the past. These vessels, however, are still used for trolling when fishing for certain types of game fish. As a consequence, unless a separate trolling motor is installed on the vessel, the primary propulsion system must be used. However, depending upon engine output and prop configuration, a desirable trolling speed of between 1.5 and 5 knots is often times impossible. Therefore, operators of such vessels must install a thrust mitigating device to decrease the propulsion efficiency of the watercraft. This device is generally referred to as a trolling plate.
Trolling plates are generally a structure that is attached to the secondary drive components of outboard or outdrive systems, usually by way of the anti-cavitation plate. These structures then are positioned directly in the thrust path of the prop, thereby reacting with the volume of water displaced by the prop in a rearward direction. As a consequence of placing the trolling plate in a trolling position and operating the drive system at idle or low speed, the propulsion system becomes inefficient, thereby decreasing the speed of the vessel.
Conventional trolling plates such as THE HAPPY TROLLER sold by Idea Development Company of Sequim, Washington, essentially rely on a mounting bracket attached to the secondary drive unit that has at its aft end a rotationally linked thrust reaction plate. The plate has an upper U-shaped portion that is adapted to receive a shaft horizontally and laterally positioned in the bracket. Slightly forward of this shaft is a spring loaded selector bar that selectively engages notch pairs formed in the U-shaped portion of the plate. This selector bar extends through the bracket so that when the plate reacts on the selector bar via the notches, it transmits forces to the bracket via the holes in the bracket that supports the selector bar.
While the described structure accomplishes the intended purpose of transmitting thrust forces from the prop to the drive unit, it does so via notches and holes formed in sheet material, usually aluminum, that may become worn over time, and are especially subject to excessive wear and potential failure when presented with high force thrusts that may emanate from high output engines or accidental over revving. It is thus desirable to have a trolling plate that is adapted to fit the secondary drive unit of an outboard or inboard/outboard drive system, but wherein thrust forces from the prop are transferred to the drive system by distinct linkages as opposed to using a notched plate to bracket to outdrive means.